Isonomia (ἰσονομία "equality of political rights," from the Greek ἴσος isos, "equal," and νόμος nomos, "usage, custom, law,") was a word used by ancient Greek writers such as Herodotus and Thucydides to refer to some kind of popular government. It was subsequently eclipsed until brought back into English as isonomy ("equality of law").
Ancient usage 
Mogens Herman Hansen has argued that, although often translated as "equality of law," isonomia was in fact something else. Along with isonomia, the Athenians used several terms for equality all compounds beginning with iso-: isegoria (equal right to address the political assemblies), isopsephos polis (one man one vote) and isokratia (equality of power).
When Herodotus invents a debate among the Persians over what sort of government they should have, he has Otanes speak in favor of isonomia rather than democracy, although the description he provides is close to the Athenian practice of democracy:
The rule of the people has the fairest name of all, equality (isonomia), and does none of the things that a monarch does. The lot determines offices, power is held accountable, and deliberation is conducted in public.
Thucydides used isonomia as an alternative to dynastic oligarchy and moderate aristocracy. In time the word ceased to refer to a particular political regime; Plato uses it to refer to simply equal rights and Aristotle does not use the word at all.
Later use 
According to Hayek, isonomia was championed by the Roman Cicero and "rediscovered" in the eleventh century AD by the law students of Bologna whom he says are credited with founding much of the Western Legal Tradition.
Isonomia was imported into England at the end of the sixteenth century as a word meaning "equality of laws to all manner of persons". Soon after, it was used by the translator of Livy in the form "Isonomy" (although not a direct translation of isonomia) to describe a state of equal laws for all and responsibility of the magistrates. During the seventeenth century it was gradually replaced by the phrases: "equality before the law", "rule of law" & "government of law".
Political theorist Hannah Arendt argued that isonomy was equated with political freedom at least from the time of Herodotus. The word essentially denoted a state of no-rule, in which there was no distinction between rulers and ruled. It was "the equality of those who form a body of peers." Isonomy was unique among the forms of government in the ancient lexicon in that it lacked the suffixes "-archy" and "-cracy" which denote a notion of rule in words like "monarchy" and "democracy." Arendt goes on to argue that the Greek polis was therefore conceived not as a democracy but as an isonomy. "Democracy" was the term used by opponents of isonomy who claimed that "what you say is 'no-rule' is in fact only another kind of rulership...rule by the demos," or majority.
The public administration theorist, Alberto Guerreiro Ramos, reserved for isonomy a central role in his model of human organization. He was particularly concerned with distinguishing the space of the isonomy from that of the economy. Following Hannah Arendt, Guerreiro Ramos argued that individuals should have the opportunity to engage with others in settings that are unaffected by economizing considerations. The isonomy constitutes such a setting; its function is to "enhance the good life of the whole."
See also 
- Athenian democracy
- Equal justice under law
- Equality before the law
- USS Isonomia (1864)
- Henry George Liddell, Robert Scott, A Greek-English Lexicon
- The Athenian Democracy in the Age of Demosthenes", Mogens Herman Hansen, ISBN 1-85399-585-1, P.81-84
- Herodotus 3.80
- Thucydides 3.82, 4.78
- Demosthenes 15.18
- Euripides, The Suppliant Woman, 353. Ste Croix (1981) 285
- Herodotus 5.92
- Thucydides 4.78
- Thucydides 3.82
- Plato, Republic 563b
- Perseus Project search
- Friedrich A. Hayek, Origins of the Rule of Law
- Hannah Arendt, On Revolution (London: Penguin Books, 1963), p30
- Guerreiro Ramos, A. (1981). The new science of organizations: A reconceptualization of the wealth of nations. Toronto: University of Toronto Press. p. 131.